Leonid Kozyarchuk, born on 11^th of May, 1965, in the USSR (Volyn Oblast, now Ukraine) is a long-term constructor and enthusiast of rotorcraft and trikes. At the turn of 1990’s he studied at the Kharkov Institute of Aviation. He is one of the founders of the Kometa company from the city of Rozhyshche founded in 1993. Between 1996 and 2001 he was a trikes design engineer at the Aeros company in Kiev. Later, between 2001 and 2011 he was a private entrepreneur dealing with manufacturing of parts and components for ultralight aircraft. Over the years Mr Kozyarchuk constructed several ultralight autogyros. For the first one – the LK-1 (built in 1987) – he was awarded one of the national prizes of the USSR. He also published multiple books – mentioned above catalogues and others dedicated to trikes and designs of Mr Igor Bensen. He, however, does not limit his writing scope to aviation.

Marcin Ruszkowski was born in 1984 in Poland. He studied Aerospace Engineering at the Warsaw University of Technology. After graduating he spent several years working hands-on with commercial helicopters as a maintenance engineer in Polish Medical Air Rescue and other companies. In 2013 he joined the design team of the Helipark GmbH company, which was at that time during the endeavor of designing a small two-seat helicopter. Later he decided to dive deeper into the software engineering world and since late 2014 he works at Leon Software – a well known in Europe scheduling and sales software provider for business aviation and small airlines. Aside from his professional career Mr Ruszkowski is passionate about rotorcraft, its design, history and all related subjects, but with stronger accents put on the technical aspects of these fascinating machines. He – like Mr Kozyarchuk – keeps collecting data on every manned rotary-wing machine he encounters. In the era of the Internet this data stack grows very quickly, so in order to properly store those data he develops in his spare time an Internet page which helps him to organize those data: rotorcraft.info - which, frankly, is also an incomplete and unfinished page.